Such sectioning or level-sealing sealing devices are known. They are used to separate different levels in a borehole in rock, which borehole should be used, for instance, as energy well or water well. Surface water can flow into such holes and contaminate, for example, drinking water so that it tastes of earth or carries contaminants from surface water. Moreover, different layers at different levels in rock can be punctured and short-circuited via the hole. This may result in the water in the hole being contaminated or other holes being contaminated via these rock layers so that undesirable effects occur, such as contamination or pressure drop. For instance, salt deposits at a depth of 100 m can easily contaminate a water well and make the water unfit for human use. An energy well is usually between 100 and 200 m deep. Normally at least one sealing device is to be used to seal against inflowing surface water, but a plurality of sealing devices may just as well have to be used for sealing at different levels in the hole.
The prior-art sealing devices that have been used up to now must, however, be specially adjusted to each hole since the quality of the rock around the hole determines whether the hole will be even and straight or whether, for instance, the hole will be slightly larger than intended since the surface of the hole has poor cohesion and will be rough. In addition, harder or smoother kinds of rock enclosed in an otherwise uniform rock may result in the hole, when being drilled, not extending perfectly straight. Moreover the drill bit is gradually worn away in use and will obtain a smaller diameter. This results in a reduction of the diameter of the hole as well.
The prior-art sealing devices are often made of PE material by turning in a lathe. All in all, this means that the sealing of the hole will be very labour-intensive and thus very expensive. Drilling in rock is in itself an expensive process and consequently this does not make installation less expensive.